In many manufacturing operations, particularly in the manufacture of cylindrical containers such as two-piece, ferrous or aluminum cans, it is necessary to mass transport such articles, either in single file or en masse. Such containers are characteristically quite unstable, particularly at present-day line speeds which are capable of handling up to approximately 2,500 articles per minute.
Present-day aluminum, two-piece cans possess can bodies having almost paper thin side walls. During processing, the can bodies are caused to engage a number of work areas including washing, decorating and necking stations. When moving from one station to the next, the can bodies either travel on a moving belt or, more advantageously, upon an air conveyor consisting of a plenum having openings for the directional supply of air from the upper deck surface. Devices of this nature are described in U.S. Pat. No. 4,456,406, the disclosure of which is incorporated herein by reference. However, it is oftentimes necessary to change the vertical orientation of the can bodies as well as to convert the flow of cans from an en masse multi-row configuration to a single file orientation, particularly when the can bodies are to be decorated and necked.
Air single filers, euphemistically known as doubling boxes, are exceedingly well known in can processing operations. For example, one such device is disclosed in U.S. Pat. No. 4,182,586, the disclosure of which is hereby incorporated by reference. Conventionally, the input or upstream end of the air single filer would be fed by a waterfall which, as the name implies, simply consists of a curved slide which transcribes a circular drum across which cans travel while rotating 90.degree. to achieve a horizontal orientation, at which point they fall into the upstream end of the single filer. A curved top guide surface prevents the cans from tumbling due to the small clearance between the guide and the top of the can.
The use of a waterfall in feeding a single filer, or any other device for that matter, possesses a number of inherent shortcomings. Quite obviously, the dropping of cans en masse from a waterfall to a lower collection area can and oftentimes does result in damage being inflicted to the container side walls. This is a particular problem today as aluminum beverage containers have been provided with exceedingly thin side walls as an aluminum saving expedient.
When the flow of container bodies was to be interrupted, prior waterfall installations would employ a gate which would physically impede the entrance to the single filer which, itself, oftentimes causes can damage. The gate regulates can flow by capturing a row of cans laterally across a conveyor with a pressure pad that clamps the row of cans between the pad and the conveyor deck surface. When the gate is closed, the pad is applied which clamps the cans, thus stopping the flow. When the gate is open, the pad is released and the cans are free to move. The clamping action applies a force to the can bodies which can result in their damage.
When the can bodies slide through a prior waterfall, an oxide coating can deposit on the guide surfaces. This coating must be removed periodically to avoid jamming. Further, the sliding action of the open end of the can body on the top guide can cause damage to the open end of the can.
It is thus an object of the present invention to provide a drum device and its method of operation as a substitute for waterfall installations of the prior art.
It is yet a further object of the present invention to provide a drum device and its method of operation capable of rotating can-shaped objects from a first to a second location over a curved surface while avoiding damage to the can bodies and providing a positive means of flow control while avoiding gate structures employed by the prior art.